Topic: OM602 swap

[EJMFS]

Hello everyone!  New guy here.  I have been reading lots of very informative posts since I decided to take on this project.  I have a mercedes benz om602 diesel engine that is going into a 79 toyota pickup.  I originally planned on using a w56 transmission but now I am debating on going with an r151f.  I have two gear driven 21 spline transfer cases, one with a top shift other with forward shift. 

Basically my choice in transmissions comes down to what flywheel would be best to use.  The crankshaft has an 8 bolt flange and across the center the bolt holes are spaced 75mm oc.  The outer diameter of the mercedes ring gear is about 307 or 308mm.  The hole in the center of the flywheel is 45.75mm.  I see that the flywheel for the 3.0 v6 toyota has an 8 bolt pattern and I have been unable to locate detailed dimensions past that.  I can make an adapter spacer if needed but would rather not in case of added vibrations.  I am ok with drilling or machining the toyota flywheel.  The more important piece of information I need is the outer diameter and center hole diameter of the v6 flywheel.  Since the v6 flywheel has the 8 bolt mount I think it may be a better choice for ease of drilling new holes.  If this is doable I will start looking for an r151f.

I greatly appreciate any information anybody has. 

I haven't found anyone else that has done this swap.

[EJMFS [OP]]

Ok, so I found the dimensions for the toyota 3.0 flywheel.  It is 12.25" od.  The original benz flywheel is 12.125".  So with only 1/8" difference I think the v6 flywheel will work.  I am planning on drilling new bolt holes in the flywheel unless I get really lucky and they are the same.  I ordered the flywheel so when I get it I will then determine what to do with the center hole and pilot bushing.  So now I am looking for an R150 or R151F transmission.  I see that it is possible to adapt the 21 spline cases to the r series transmission with an input shaft from marlin.  I will post some photos of my work as soon as I get the flywheel.

[emsvitil]

Are both flywheels neutral balanced?

[EJMFS [OP]]

Thats a good question.  The mercedes flywheel has a few partially drilled holes that the factory used to do some balancing but that doesn't tell me anything.  What is a good way to check the balancing?  Is it very difficult to match the balancing of the two?

[EJMFS [OP]]

Ok, so I got the flywheel for the r150.  Now it's time to build a balancing jig to match it to the original benz.  The bellhousing will need to be cut back about 1" and I will make a new mounting flange drilled for the mercedes bolt pattern.  The flange will be welded to the trimmed bellhousing.  The bolt holes for the toyota flywheel are a slightly smaller spacing and the center hole is about 3mm too small.  I need to find a machine shop to make these corrections before I balance it.  So if anyone knows of a machinist in the Portland area that would do this let me know.  I am also looking for the r150 transmission.

[ccolby]

Here are a few links that were helpful to me. I'm in the process of putting a OM617 into a 88 4runner.
http://www.4x4labs.com/products/diesel-conversions/om617w56/
http://www.4btswaps.com/forum/forum.php
http://www.superturbodiesel.com/std/
http://www.yotatech.com

There a lot of information on these sites.
Good luck, and let me know if you need any help.

[12 valve]

The om617 sounds like fun I have an 87 4runner I would like to put one in.

[EJMFS [OP]]

Ok, so just to clarify things I am using an om602 engine.  This is not the same as the om617.  
I got the transmission today. It is an r150f if I am correct.  The reason for choosing this transmission is for the size of the flywheel.  the flywheel for this transmission is only 1/8" over the diameter of the original flywheel and it also has an 8 bolt pattern to the crankshaft.  The bolt holes will need to be slotted about 1mm out from original pattern and the center hole will be machined to about 2mm larger than original diameter.  I have yet to figure out the pilot bearing dimensions.  I am planning on cutting the bell housing down to compensate for the difference in backspacing.  I will need to weld in a new flange that is sized to the mercedes bolt pattern.  I am also looking at the starter and gear compatibility.  Looks like I may be taking the starter gear off of the toyota V6 starter and fitting it onto the mercedes starter motor.

[emsvitil]

Rather than slot the 8 holes, why wouldn't you just drill 8 more between the 8 at the proper pattern?

[EJMFS [OP]]

I thought about offsetting the pattern but the only thing I don't like about that is the positioning of the lineup pin on the crank flange.  I want to make sure the line up pin fits nice and snug.  If I were to drill a second offset bolt pattern the pin would be landing just off center in one of the unused holes.  the toyota holes are very close to where they need to be for the benz already.  The slot will be less than 2mm.   I am taking the flywheel to the machine shop today.  Sounds like the machine work will be about $60. 

The next step will be to get the starter setup.  I'm hoping I will be able to use the gear from the toyota starter on the benz starter since the benz starter actually bolts to the engine block.  And the toyota starter looks to be too small and weak for the diesel compression.

[EJMFS [OP]]

I just did some rough measuring of the engine bay.  I will have to build a custom sway bar that mounts farther forward.  If anyone has any tips on building a swaybar let me know.  I have never done anything like that before.  The benz oil pan drops down right where the sway bar is but luckily it has plenty of clearance around the axle housing.  And of course it will need a custom radiator support to move the radiator as far forward as possible.  I hope I won't have to cut the firewall but if so I am prepared to do so. 

[emsvitil]

Did you see this thread:

http://board.marlincrawler.com/index.php?topic=74431.0

[EJMFS [OP]]

Ya, thanks for the link.  Very interesting build.  So I took the flywheel to the machinist today.  Good news there.  He said he could take the ring gear off of the benz flywheel and fit it to the toyota flywheel.  So that saves me from having to modify the starter.  Now I will just need to get a pilot bearing and figure out what type of bushing I will need to make to fit that.  Or maybe I'll just get a custom sized bearing from Mcguire bearing.

[ccolby]

My Buddy built my pilot bearing for my OM617 to Toyota 3.0 flywheel. It takes the stock pilot bearing. I'm finally getting ready to work on mine. I cut my adapter plate out of 3/8 plate.

[aglicknmex]

RE FLYWHEEL DRILLING
Done this swap but having some shaking,  and  wondered how EJMFS did his flywheel mod??   I used the R150 series tranny with 8 hole flywheel.   4 holes line up perfectly(centered on custom pilot bearing holder inserted in crank) Rest of the holes were off, but cut into existing holes more than I cared to elongate.    I tapped and threaded the holes that didnt fit and then epoxy-ed studs into the holes and ground flush.  Then drilled the rest of the holes.  I 'm not real happy with the arrangement and am looking for alternatives   I would love to get an undrilled flywheel for a v-6 and just put the holes in the right places!!

Thanks guys for any help!!

[EJMFS [OP]]

I took the v6 flywheel and the mercedes flywheel to a machinist.  He scanned the bolt pattern and center hole of the mercedes flywheel and uploaded to his computer.  He used a cnc mill to do the cuts.  The center hole was bored out to match the mercedes crank flange and the bolt holes were very slightly slotted probably only 1mm.  He also removed the toyota ring gear and cut the outer diameter to a press fit for the mercedes ring gear to be used.  This allows me to use the mercedes starter without further modifications.  It runs smooth and the starter engages properly.  It was well worth the money to pay for this machine work.  I did make the adapter ring with a lathe to fit the toyota pilot bearing.  This was relatively easy with a manual lathe.
Sorry for the delayed response, I haven't been on in a while.  Hope this helps

[MikeGee]

How goes the swap man? Registered to the forums because of this post haha. Venturing into a diesel swap on my 1991 4runner. You have pics and updates? Was planning on a 617 but just ran into a 602 for sale locally for 300 so contemplating this swap...On the oil-pan is it possible to just notch the pan or is it smack dab on the sway-bar? For the bushing do you happen to have the dimensions written down? How thick is the adapter plate your going to use? Sorry for the one hundred questions but it seems your the person to ask thus far into my research.(Not too many have been posted) Have access to a friends machine shop so wondering if i should try it myself or just shell out the cash on the flywheel and get a shop to do it.

[EJMFS [OP]]

So if you are still considering doing this swap I can say that I am very pleased with the truck now that it is done.  Drives great, gets great fuel economy and so far is very reliable.  It was a lot of work and took a lot of research but now it is done.  So if anyone wants to do this swap I would be happy to give my input.  This engine is much lighter than the om617 and is more efficient.  I am actually getting ready to build an om602 turbo that will have quite a bit more power.  The non turbo gets around just fine and seems to be a bit more powerful than the stock 20r.  However, I use this mainly as a work truck and the turbo would be nice when hauling and driving through the mountains.


So for your questions MikeGee.  I just removed the sway bar and it didn't seem to make much of a difference in driving.  I also have 3" lift springs with rancho 9000 shocks with the shocks adjusted for more stiffness.  I would not advise notching the pan.  I had to do a lift after the swap because the sump was only about 1.25" from the trailing arm allowing the arm to hit the oil pan.  Before the lift I just added blocks over the bump stops to only allow about .5" suspension travel.  So needless to say this was not a comfortable ride nor a permanent solution.  For the adapter plate I used 3/4" aluminum plate.  The backspacing needed to be reduced on the bellhousing so I cut the bellhousing back to the appropriate spacing minus the 3/4" and welded the new flange to the bellhousing.  I recommend using a TIG welder for this unless you are some kind of rockstar with aluminum MIG.  I think if you have access to a mill you should be able to do it fairly easily.  You may need a rotary table to trim the perimeter in order to fit the benz ring gear.  The bolt holes only needed about 1mm of slotting.  And also, I had to remove the bolt holes for the slave cylinder so I used a pull style slave cylinder.  I did read about someone else using a concentric slave cylinder from a chevy colorado which has a slightly different version of the aisin r150f.  That guy used the whole front bearing retainer assembly from the colorado.

[EJMFS [OP]]

a few photos

[EJMFS [OP]]

a few more

[greeny]

Awesome build dude!

[helipilot77]

Your gonna love runnin on diesel. Looking good. I bet it feels good to have that engine in its home.

[emjay520]

Hello, I just ran across your thread via Google and I have a few questions.  I am doing a OM602 swap of my own from a 1990 300D, mine however is a turbo motor vs NA. What all wiring did you need from your donor vehicle to complete your swap?  For my swap I am planning on using a manual glow plug controller and the stock Mercedes transmission, you think that this will be fine or is there a Mercedes computer that installs easily?

[EJMFS [OP]]

As for the wiring I did start out with some problems with the factory toyota wiring so I eliminated every circuit that wasn't needed from that and left the lighting and dash circuits.  I put in all new wiring for the alternator and used an aftermarket relay to cut the coil power when the engine shuts off.  The glow plugs harness and relay was pulled from a mercedes and integrated into the toyota ignition switch.  The toyota starter solenoid wire was just hooked up to the benz starter.  There is a vacuum valve and a solenoid valve that both need to be hooked up to the ignition circuit.  The vacuum valve mounts to the top of the intake and the solenoid valve is on the back side of the injection pump.  I recommend using a relay to energize these two coils so they don't tax the ignition circuit too much.  The toyota voltage regulator that mounts on the fender was removed because the benz alternator has an integrated regulator inside the alternator.  And that's pretty much it.  I didn't use any computer in mine but your transmission may need it if it is an automatic.  I believe the 90 is a mechanical injection system so I don't know why the engine would need a computer unless it has to sync the shift points to the rpm which I think happens in the tachometer circuit.  There is a magnetic pickup next to the flywheel that senses the engine rpm.  Hope this helps and good luck with your swap!

[moroza]

The thread's a bit old; hope it's ok to revive?

I also found this swap via a Google search, planning my own diesel swap. What you've done looks like a good, clean installation. My hesitation to use an OM617 - weight and fuel economy - seems largely solved by using the later OM602. However, info is much harder to find for that engine, so I have some questions for the OP:

How long is this engine, and do you think that it could be squeezed in without chopping the radiator crossmember, perhaps if there's no internal fan?

You mention that the oilpan hits the "trailing arm". Do you mean the stock tierod? In one of the photos, it looks like the engine is mounted quite low. Do you think there's room to mount it higher, closer to the hood, and not have to do a lift?

[PixelPIRATE]

   I have a '81 Long Bed and have been thinking of this swap for years.  You are the first person I've seen pull it off in a 1st Gen while keeping the radiator up front.  Really cool !!!   Like moroza I'm curious how much lower the tranny and t-case are mounted vs stock.